The progressive increase of food waste in America and its environmental impact.

1Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, United States of America. kevinh@niddk.nih.gov

Abstract

Food waste contributes to excess consumption of freshwater and fossil fuels which, along with methane and CO(2) emissions from decomposing food, impacts global climate change. Here, we calculate the energy content of nationwide food waste from the difference between the US food supply and the food consumed by the population. The latter was estimated using a validated mathematical model of metabolism relating body weight to the amount of food eaten. We found that US per capita food waste has progressively increased by approximately 50% since 1974 reaching more than 1400 kcal per person per day or 150 trillion kcal per year. Food waste now accounts for more than one quarter of the total freshwater consumption and approximately 300 million barrels of oil per year.

(A) The average adult body weight (Δ) as measured by the National Health and Nutrition Examination Survey. (B). Per capita U.S. food availability unadjusted (○) and adjusted for wastage (▪) according to the United States Department of Agriculture (USDA). The solid curve represents the mathematical model prediction of average food intake change (dashed curves indicate±95% confidence intervals). (C) Energy content of per capita U.S. food waste predicted using our mathematical model (solid curve, left axis). The right axis plots the per capita annual mass of municipal solid food waste (▴). (D) Percentage of available food energy wasted as calculated by previous USDA estimates (▪) and predicted using our mathematical model (solid curve).

(A) The experimentally imposed increases of food intake during controlled over-feeding experiments (black bars) along with model predicted values (white bars) calculated using the measured body weight changes. (B) Model predicted relationship between changes of 24 hour energy expenditure and body weight change after 3.6 years of over- and under-feeding (♦) along with the best-fit regression line determined from longitudinal measurements in a cohort of Pima Indians followed for the same average time interval. (mean±SD).